The limbic system

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The limbic system

Neuronal circuitry
controls of
emotional behavior and motivational
drives

Composed of subcortical and cortical
components
Limbic System
Figure 12.18
limbic
Subcortical group
Hypothalamus ,septum,paraolfactory
area,epithalamus,ant.thalamic
nuclei,hippocampus,amygdala,basal gangeli
Limbic cortex
 Orbitofrontal
coretx,subcallosal
gyrous cingulate gyrus and
parahippocamp gyrous
Limbic System: Emotion and
Cognition

The limbic system interacts with the prefrontal
lobes, therefore:
One can react emotionally to conscious
understandings
 One is consciously aware of emotion in one’s life


Hippocampal structures – convert new
information into long-term memories
The hypothalamus not only
influences how you feel, it
influences how you interpret
the consequences of those
feelings.
limbic
Hypothalamic Role in Emotion
Visceral
Afferents
Hypothalamic
Nuclei
Hormonal
Output
Nucleus
of the
Solitary Tract
Target
Organs
Autonomic
Output
Brain Stem
Nuclei
Autonomic
Preganglionic
Nuclei
Hypothalamus
Pituitary
Releasing Factors
Adenohypophysis
(Anterior Pituitary)
Autonomic
Nervous System
Neurohypophysis
(Posterior Pituitary)
Sympathetic
Parasympathetic
“I feel fear!”
stria
terminalis
mtt
Cortex,
septum
Amygdala
medial forebrain
bundle
Anterior Nucleus
dorsal long.
fasciculus
Brainstem
medial
forebrain
bundle
Brainstem
spinal cord
Hypothalamus
ventral
route
ant.
Amygdala
parvo
magno
(SO, PV)
Pituitary
post.
Hypothalamus,Major


Hypothalamus is the most important output
sorce
It communicate with brain stem by medial
forebrain bundle ,bidirectionaly between
forebrain and brain stem
Hypothalamus cont.

Controls:
1-vegetative and endocrine functions
2-behavior and motivation
vegetative and endocrine functions

Cardiovascular regulation involves
1-Post. And lateral hypothalamus area, increase
BP and HR.
2-preoptic area ,decrease BP and HR
*1and 2 mediated by cardiovascular centre in
the pontile and medullary part of reticular
formation
Body temperature regulation

Preoptic area
Thermo-regulation
(body temperature)

Involves autonomic nervous, endocrine, and
skeletomotor systems

Body temperature detectors


Peripheral: skin, spinal cord, viscera

Central: anterior hypothalamus
Body temperature effectors

Heat retention or generation:
posterior hypothalamus

Heat dissipation: anterior hypothalamus
Thermo-regulation
(body temperature)


Heat dissipating mechanisms

Dilation of blood vessels in the skin

Inhibition of shivering
Heat conserving mechanisms

Vasoconstriction of blood vessels in the skin

Shivering

Increased secretion of thyroxin
Response to Cold
Response to Heat
Methods of thermo-regulation by the body
Regulation of body water intake



Thirst centre,lateral hypothalamus
Electrolyte concentrationmaking desire to drink
Supraopticx:urinary excrition due to ADH
Thirst

Function of serum osmolality and blood volume

Osmotic receptors in the hypothalamus

Volume receptors in the right atrium of the heart
and great veins

Vasopressin release from hypothalamus
 Increases
water reabsorption from the
 Inhibited
by ethanol
kidney
Circadian Rhythm


Oscillations during the course of the day

Corticosteriods

Feeding and drinking behavior

Growth hormone secretion
Lesions of the suprachiasmatic nuclei of
the hypothalamus disrupts these oscillations
Control of Feeding
Feeding


Complex interaction of many systems
Regulation of energy metabolism by the
Ventromedial and Lateral nuclei of the
hypothalamus

Physical Lesions produce hyperphagia and obesity
or reduced attention to food.

Amygdala may also be involved indirectly
 Lesions produce hyperphagia-like symptoms

Ventromedial hypothalamic lesions also cause
increased insulin secretion
Obesity.
Feedback Mechanisms Controlling
Feeding

Feedback from gut hormones
 e.g. Cholecystokinin
 Released from small intestine in response
to feeding
 Inhibits or suppresses feeding
Uterine contraction and milk
ejection

Oxytocin stimulation by PARAVENTRICULAR
‫هسته آميگدال و ارتباط آن با نواحي مختلف‬
‫مغز‬
‫ارتباطات عصبي سيستم ليمبيك‬
‫ارتباطات اصلي شكنج سينگوال‬
‫مسيرهاي پردازش اطالعات‬
Hippocampus circuit

Ent. cortex From perforant To dentate gyrous
mossy fiber cA3 schaffer collaterals cA1 to
subiculum to ento cortex
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